Metro rail construction can introduce localized environmental disturbances during the development phase despite its long-term benefits for sustainable urban mobility. This study evaluates the air and noise pollution impacts of ongoing Chennai Metro Rail construction across Corridors 3 and 4, covering pre-monsoon, monsoon, and post-monsoon seasons. Air-quality monitoring was conducted for key pollutants—PM2.5, PM10, SO2, NO2, and CO—using high-volume air samplers and portable analyzers, while noise levels were continuously recorded using digital sound level meters. Spatial mapping with GIS illustrated pollutant dispersion and identified localized hotspots of high particulate and acoustic loads. Results indicated pronounced seasonal and spatial variability in particulate matter concentrations across construction corridors, with PM10 levels peaking during the pre-monsoon period. Although average particulate concentrations largely remained within National Ambient Air Quality Standards, statistically significant seasonal differences were observed. Noise levels frequently approached or exceeded CPCB limits, particularly near densely built commercial corridors. Correlation analysis revealed a significant positive association between PM2.5 and PM10, indicating common emission sources primarily related to construction activities and associated vehicular traffic. Health surveys indicated that nearly half of the nearby residents reported dizziness and other discomforts, along with respiratory and ocular irritation, which were spatially associated with areas of elevated air and noise levels. The findings indicate that metro construction can generate measurable localized environmental and public health stress, yet these impacts are temporary and can be mitigated through dust suppression, acoustic barriers, and controlled scheduling. Integrating real-time monitoring, community engagement, and adaptive environmental management can transform metro projects into resilient pathways toward sustainable urban development.
Das et al. (Wed,) studied this question.